1. Field of the Invention
The present invention relates generally to image and video processing.
2. Description of the Background
For applications such as advertising, sports and entertainment, it is often desirable to take a set of images of an object from a large number of cameras that surround the object, and then play back those images in sequence to create an effect as if one is flying around the object. This special effect is sometimes referred to as the “fly-around” effect. A subset of the fly-around effect is when the displayed images are all from the same instant in time; this is sometimes referred to as the “3D stop-motion” effect. If the cameras are positioned in a closed-ended configuration, such as a circle or ellipse, the effect is sometimes referred to as the “spin-image” effect.
FIG. 1 illustrates one known technique for realizing this effect. As illustrated in FIG. 1, multiple cameras are set up in a ring, fixated on a single point of interest (PO) in space. Playing back one frame from each camera creates the appearance of spinning around the POI. Furthermore, playing back frames from a single time step, across all cameras, yields the appearance of freezing the action in time while a virtual camera spins around the frozen actor.
The process of taking images for this purpose is tedious and costly. First, all cameras must be aligned with great precision so that their central viewing rays pass through the same POI on the object. Otherwise, the set of images when played back will appear bumpy and jittery. In addition, after the set of images are taken, one may want to alter the POI around which to create the fly-around effect. This typically involves reorienting the cameras and retaking a whole new set of images. These two difficulties are compounded when dealing with an unsupervised moving object or a dynamic scene (rather than an actor following instructions). There may not be time to align all of the cameras to satisfy the condition that all central rays intersect at the POI, and the object motion may not occur again in the same place. It may also not be possible to align some of the cameras with the POI due to constraints on their allowed motions.